Bill's partner with new diet consumed 84 starters and felt better as a result (9)
I believe the answer is:
Here is my best explanation:
'felt better as a result' is the definition.
'bill's partner with new diet consumed 84 starters' is the subsidiary indication.
'bill's partner' becomes 'ben' (bill and ben the flowerpot men).
'with' says to put letters next to each other.
'new' indicates an anagram.
'consumed' indicates putting letters inside.
'84 starters' becomes 'ef' (the first letters of Eighty-Four).
'diet' anagrammed gives 'ited'.
'benited' enclosing 'ef' is 'benefited'.
'and' is the link.
(Other definitions for benefited that I've seen before include "reaped financial reward" and "Gained".)